Process and apparatus for the production of flat bags



Sept. 13, 1938.

c. HOLWEG 4 PROCESS AND APPARATUS FOR THE PRODUCTION OF FLAT BAGS I Filed May 17, 1935 2 Sheets-Sheet l I I fnvenfan 6M W Sept. 13, 1938 c. HOLWEG 2,129,842

PROCESS AND APPARATUS FOR THE PRODUCTION OF FLAT BAGS Filed May 17, 1935 2 Sheets-Sheet 2 Patented Sept. 13, 1938 UNITED STATES PATENT OFFICE PROCESS AND APPARATUS FOR THE PRO- DUCTION 0F BAGS Application May 17, 1935, Serial No. 21,952 In Germany June 26, 1934 11 Claims. (01. 93-18) The invention relates to a process for the producing of flat bags from a continuous paper web, which is formed into a tube and then cut into sections, whereupon one end of the sections is turned over to form a bottom flap. The tubular sections must be separated from each other in such a way that one end projects a little over the other, as otherwise a simple folding-in of one end of the tube is not sufficient for obtaining a perfect closure of the bottom.

In'general therefore for separating the sections of the tube from the web the strike-off method is employed, which consists in striking off the upper and lower parts of the tube at the same time along two scalloped lines by means of a striker which is moved transversely across the web. The striking-off, however, causes an unpleasant noise; while, when the struck-off tube sections are carried along, interruptions are often caused by the arriving bags being jammed up or crumpled. The strikers are moreover very dangerous for the machine tenders.

To avoid the difiiculties in the sepa ation of the tube pieces by a striker, it has already been proposed to produce in the continuous paper web from which the bags are made, either before or after the formation of the tube, lines of perforation defining the closure flaps which are subsequently to form the bag ends. The final separation of the foremost sections of the tube is then effected by a traction effort exerted thereon by suitable means, for example rollers having a higher peripheral speed than that of movement of the tube. However, the separation is effected already well before the tube sections are engaged by the bag-end forming device, so that these sections are obliged to travel for a certain distance as, individual pieces which are in some cases subjected to further operations and are in all cases exposed to the same risks of tangling, jamming and crumpling as the sections separated by striking.

In the process according to the invention, allthese risks are avoided by the fact that the tearing or detaching of the foremost tube sections is effected by the bag-bottom forming device comprising in known manner rotative tongs cooper ating with a synchronically turning folding blade.

This process makes it possible to ensure that the web need not be or is not separated into sections before the bottom is formed or in process of forming, which not only brings about greater continuity in the working process, but at the same time a considerable simplification and standardization of the driving arrangements and, moreover, permits stoppages and interruptions of work and in this way results in an increased output capacity of the machine. Finally, the

bottom flaps may also be-given any desired shapes Figs. 4-6 show in side elevation and plan an arrangement in which the perforation is carried out before the formation of the tube.

Figs. 7-10 show an arrangement as well as various working phases for the production of bags, in which the bottom flap is on the same tube side as the upper closing flap.

According to Figs. 1-3 the formation of the tube takes place at I in the usual manner; this is drawn over the mandrel 2 shaped as a thin tongue by means of drawing roller pairs 2, which are carried in two lateral recesses in the mandrel. Behind these drawing rollers the mandrel is at 3 hollowed out like a comb, and two rollers 4 are arranged at this place one above and one below the mandrel and these rollers are provided with a perforating device 5, the points of which pass into the teeth in the comb without touching one another. The perforating devices can be shaped in any desired manner. It is preferable that they should make a straight line for one side of the tube and a curved line for the other.

The tube thus prepared leaves the mandrel and by means of a further pair of drawing rollers 6 having the same peripheral speed as 2' it is carried to the folding apparatus I of a construction already known per se. As the periphera speed of the latter is greater than the travelling speed of the arriving already perforated tube, the foremost of the already perforated tube sections can be separated off without dimculty at the perforated places;

Owing to the fact that the separating-off of the tube section takes place only after the section has already been gripped by the folding apparatus, a. special conveying device, such as was previously indispensable for the separated-off tube sections, can be dispensed with. The drawing roller pair 6 canalso be moved much further back, so that their positionis behind the first perforated position of the already perforated tube. Their distance from the folding apparatus 1 can moreover be varied within wide limits in order to make allowance for the different lengths of bag.

The closing of the bottom of the bag can be effected in the usual manner by the folding apparatus.

In the example of embodiment shown in Figs. 4-6 the perforation of the web I is effected before v the tube is formed. Owing to this, in the first l the tube were otherwise perforated and which owing to the friction of the driving rollers is exposed to a considerable amount of wear, is dispensed with. The shaping plate which forms the tube can also be made adjustable in width in the known manner.

As'can be seen, the paper web after being unwound in the known manner is provided by the pasting wheel II with a longitudinal coating of paste, a roller l2 taking up-the counter-pressure. This roller can either be covered with rubber, or it may have a slit corresponding to the perforating device. Opposite to it a shaft I3 is mounted, which carries a perforating device M, the rotation of which corresponds to the unfolded length of the bag and which works with one revolution per bag. The shape and the size of the perforating device is made to correspond to the requirements of the bottom pasting, as well as to the shape of the desired opening flap. The perforating device can be conveniently composed, according to requirements, of straight and curved elements, like typographical printing matter. These elements may be pieces of an ordinary band saw. The means for holding these elements may also be variable in length and thickness and exchangeable.

The tube is then s'haped in the known manner around a forming plate, which may be rigid or adjustable in its width and drawn along by the drawing device 6. This drawing device is adjustably mounted in the longitudinal direction,

with a view to permitting never more than one line of perforations 9 between the drawing device 6 and the folding apparatus 1. The drive of this drawing device is effected by means of intermediate wheel l6-through the shaft I5 of the folding apparatus, upon which a change speed wheel "is fastened.

At the given moment the folding blade l8 can in the known manner seize hold of the projecting end of the tube which is to form the bottom and owing to its greater speed in relation to the drawing device 6 it can finally separate the tube along the line of perforations 9. For relieving the folding knife a fillet Ill can be arranged near by it, which by pressing on the lower folding roller seizes the necessarily projecting bottom end and gives to this part of the tube in a positive manner the acceleration necessary for separation. The folding then takes place without the folding blade taking part in the separating operation and the blade therefore does not suffer from additional straining.

Figs. 'I-lOshow an arrangement for the production of fiat bags with a lower bottom flap and upper closing flap situated on one side of the tube.

With the known flat bags there is the disadvantage that the strip serving for the bottom flap and that for the closing flap lie at both ends of the tube of the bag upon opposite sides, i. e.,

the bottom flap is turned up on one side of the tube, while the closing flap is turned up on the other side of the tube. The cause of this is due to the dependence of both strips upon each other (the strips are formed, as is known, by a simultaneous separation of both sides of the tube in two different planes) which explains moreover why both flaps must always have the same shape and length. The demand now, however, exists in practice, partly on aesthetic grounds and partly on practical grounds, to turn up both flaps towards the same side of the bag, and to give them in addition different shapes and different lengths.

This is attained, in accordance with the present invention, by giving a special shape to the lines of perforation between the sections of the web. These lines are in the present case shaped in such a way, that they surround two flaps which can but ought not necessarily abut against one another, namely the closing flap of one section and the bottom flap of the next section, and the separation is effected in two stages after the formation of the tube, a first stage in which the foremost tube part before its entry into the folding apparatus is separated from the next tube, and a second phase, in which the waste which is formed between the two flaps is removed. The manner of both separations is that the forward end'of the part of the tube to be separated is seized on each occasion by members, whose speed of travel is greater than the speed of those members which are holding or retaining the part behind the perforation.

In the embodiment of Figs. 7-10 there are two lines 9, 9', of which the first forms the edge of the closing flap of the preceding section of the web, and the latter forms the edge of the bottom flap of the next section of the web. By using two lines of perforation the possibility is therefore presented of shaping the closing and bottom flaps quite independently of each other and in any desired manner. The perforating blade I4 is given the suitable shape. Before perforation the web I receives as usual a longitudinal coating of paste by means of the glue coating device H.

The tube is shaped in the known manner over a forming plate, while the pair of drawing rollers 6 supply the necessary tension effect.

Following on the formation of the tube the separation takes place in two stages. In addition to the folding apparatus 1 there is also arranged here a special pair of separating rollers 20, 2| placed in front of the folding device. One roller of this pair has a recess over the larger part of its circumference and it therefore only comes into periodical contact with its counterroller, in order to exert a drawing effect upon the tube. The peripheral speed of the rollers 20, 2| is greater than that of the drawing rollers 6. The peripheral speed of the folding apparatus I is likewise greater than that of the pair of rollers 20, 2|.

When the track has passed a little way over the contact line W, W of the two rollers 20, 2|, these two "latter come into engagement with one another; the seized tube part receives the increased peripheral speed of these rollers and a complete separation of the same from the succeeding tube takes place in accordance with the shape of the bottom flap of the next part of the tube (Figs. 8b and 9). The separated tube part is now carried along further at increased speed by the pair of rollers 20 and 2| and it travels away from the more slowly moving tube. After a certain interval of time, which is dependent upon the length of the bottom closing flap, its forward end is seized by the folding apparatus 1, while at the same time the lower recessed edge of its rear end is released by the rollers 20, 2| and only the upper paper layer of this end is still held by the rollers. The greater peripheral speed of the folding apparatus then effects the separation of the waste 23 produced between two tube parts in accordance with the shape of the closing flap of the part of the tube seized (Fig. 8C and Fig. The waste 23 is lifted through a series of points on to the roller 2| and carried downwards where it is stripped, off by a rake 25 and stored up in a container 26.

However the waste can also be removed by two or more rollers instead of by this one roller, although it would be more cumbersome and expensive to do so. 1

In orderto be able to make allowance for various lengths of bag and flap, the drawing rollers 6, the separating rollers 2|], 2| and the folding apparatus 1 are so arranged that the distances between the same can be varied.

As shown in Figs. 1 and 8C, the bag bottom is formed by folding the cut-out end about a line arranged inwardly of the cut-out portion, thus presenting a double thickness of the tube to the folding mechanism, thereby preventing injury to the tube and producing a bag having a stronger than usual bottom structure.

The further working-up of the bag is carried out in the known manner.

I claim:

1. An apparatus for manufacturing paper bags from a continuously moving paper web comprising a device for transversely perforating the web, a tube-forming device, drawing rolls for the tube, and rotative bottom-forming means operating at higher peripheral speed than said drawing rolls effective to separate a tube section by advancing it at a higher linear speed than the re- .mainder of the tube.

2. An apparatus for manufacturing paper bags from a continuously moving paper web comprising a device for transversely perforating the web, a tube-forming device, drawing rolls for the tube, rotative bottom-forming means operated at a higher circumferential speed than the drawing rolls and? a fillet on said bottom-forming means for gripping a tube section and advancing it at a higher linear speed than the remainder of the tube.

3. An apparatus for manufacturing paper bags from a continuously moving paper web comprising 'a rotating member, perforating means carried thereby, a co-operating roller having a resilient surface engageable by said perforatingmeans, a tube forming device, drawing rolls for the tube, and rotative bottom-forming means operating at higher circumferential speed than said drawing rolls effective to separate a tube section by advancing it at higher linear speed than the remainder of the tube.

4. An apparatus for manufacturing paper bags from a continuously moving paper web comprising a rotating member, perforating means carried thereby, a co-operating roller having a resilient surface engageable by said perforating means, a tube-forming device, drawingrolls for the tube, rotative bottom-forming means turning at a higher circumferential speed than the drawing rolls, and a fillet on said bottom-forming means for gripping a tube section and advancing it at a higher linear speed than the remainder of the tube.

5. An apparatus for manufacturing paper bags from a continuously moving paper web comprising a device for transversely perforating the web, a tube forming device, drawing rolls for the tube, and a rotative bottom-forming device turning at a higher circumferential speed than the drawing rolls effective to grip the fore end of a tube section to tear it away from the remainder of the tube.

6. An apparatus for manufacturing paper bags from a continuously moving paper web comprising a device for transversely perforating the web,

a tube forming device, drawing rolls for the tube, a rotative bottom forming device turning at a higher circumferential speed than the drawing rolls and a. fillet on' said bottom-forming device for gripping the *fore end of a tube section to tear it way from the remainder of the tube.

7. An apparatus for manufacturing paper bags from a continuously moving paper web compris-v ing a tube forming mandrel, a comb-like perforated prolongation and lateral drawing rollers on said mandrel, perforating rollers above and beneath the comb perforations of the prolongation, drawing rolls following the perforating rollers and a rotative bottom forming device turning at a higher circumferential speed than the drawing rolls.

8. An apparatus for manufacturing paper bags from a continuously moving paper web comprising a device for transversely perforating the web, perforating blades on the perforating device surrounding a bottom flap of one tube section and an upper closing flap of the preceding tube section, a tube-forming device, drawing rolls for the tube, periodically acting tearing rolls the circumferential speed of which is higher than that of the drawing rolls and a rotative bottom-forming device the circumferential speed of which is higher than that of the periodically acting tearing rolls.

9. In the process of manufacturing paper bags with flat bottoms .wherein a paper tube having longitudinally spaced transverse perforations dividing the same into sections of uniform length is continuously advanced at a uniform rate, the steps of folding corresponding ends of successive sections to form bag bottoms and simultaneously increasing the rate of advance movement of the section being subjected to the bottom-forming operation to separate it from the tube.

10. In a process for manufacturing paper bags with flat bottoms wherein a web of paper is continuously advanced at a uniform rate and formed into a tube, the steps of perforating the paper web to divide it into sections of uniform length, folding said perforated web into a tube, folding corresponding ends of successive sections to form bag bottoms and simultaneously increasing the rate of advance movement of the section being subjected to the bottom-forming operation to separate it from the tube.

11. In a process for manufacturing paper bags with flat bottoms and upper closing flaps turned on the-same side as the bottom wherein a web of paper is continuously advanced at a uniform rate and formed into a tube, the steps of transversely perforating the web to divide the tube into sections of uniform length, said perforations being along lines of which one is shaped like the edge of the closing flap of the leading tube section and the second is shaped like the edge of the bottom flap of the succeeding tube section, increasing the rate of advance movement; of the leading section to separate it from the tube along the second line of perforation, folding the leading end of the section to form the bag bottom and simultaneously increasing the rate of advance movement of that portion of the section ahead of said first line of perforations, thereby separating said portion from the remainder.

CHARLES HOLWEG. 

